Boot upper



FIG. 1 is a left side elevational view of a boot upper, showing my new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a rear elevational view thereof; and,

FIG. 4 is a front left perspective view thereof.

The broken lines shown on the bows are intended to disclaim the interior portions of the bows, and the broken lines illustrating the boot are solely for the purpose of illustrating context, environment or other unclaimed areas and form no part of the claimed design. 

CLAIM The ornamental design for a boot upper, as shown and described. 